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Fire Dynamics and Forensic Analysis of Limited Ventilation Compartment Fires Volume 1: Experimental

NCJ Number
Date Published
October 2009
194 pages
Since little research has been done to examine full-scale unventilated fires despite their common occurrence and relevance in fire investigations, this project was conducted in order to characterize the fire dynamics of unventilated and partially ventilated compartment fires.
Research goals were to determine the effects of ventilation on general fire dynamics, including fire growth, smoke and gas production, and vitiation; identify the effect of ventilation on tenability factors, including temperature, heat flux, and carbon monoxide; and to determine the effect of ventilation and ignition scenario on the ability to use forensic tools in analyzing the cause and progression of a fire. The study found that fires without sufficient ventilation became vitiated and ceased to grow; and fires with sufficient ventilation continued to grow. A critical ventilation size that allows the continued growth of a fire was determined. The suppression of fires was due to the reduction of oxygen and the increase in diluents, particularly carbon dioxide. Although ventilation capability ultimately influenced how large a fire could grow, the ventilation opening did not have an effect on the initial fire growth rate. For approximately the first 5-10 minutes after the ignition of the main fuel item, the heat release rate for each test was similar to others of the same fuel type and orientation, regardless of the vent opening. In terms of fuel source, sofa fires posed a faster thermal hazard than the cabinet fires, resulting in shorter times to untenable temperature and higher peak temperatures. The ignition scenario also had an effect on the time to untenable conditions within the enclosure. A series of 15 full-scale fires were performed within an instrumented, 4-room, apartment-style enclosure that measured 450 square feet. Three different fuel sources, - sofas, kitchen cabinets, and cotton batting - were tested under various ventilation schemes. Extensive figures and tables, appended supplementary data and information, and 31 references

Date Published: October 1, 2009